Gas-operated firearm



- March 1949- H. F. Mos sBERe GAS OPERATED 'IFIREARM Filed Aug. 25, 1943ATTORNEY INVENTOR Harold I-I'Mossfierg.

M miiwm mw Patented Mar. 15, 1949 GAS-OPERATED FIREARM ApplicationAugust 25, 1943, Serial No. 500,184

Claims.

This invention relates to improvements in gasoperated firearms of thesmall arm type and more particularly to mechanism retracting meanswhereby the firearm may be classed as gas-operated.

The so-called gas-operated class of firearms obtain the energy forretracting a loading and/or firing mechanism, such as a bolt, to disposeit and cooperating parts in cartridge firing position, the gas pressurerequired being obtained from the barrel during the period the projectileis propelled therethrough. In some instances the recoil action obtainedat the moment the cartridgeis fired is utilized for retracting thefiring mechanism and in others both the gas pressure and the recoilaction is used.

One object of the present invention is to provide means whereby afirearm is adapted to use both gas pressure and/or the recoil action ina novel manner whereby the firing mechanism of the firearm will beautomaticall replaced into an initial position when a cartridge isfired.

Another object is to provide means in a firearm whereby the maximum gaspressure developed in the barrel upon firing a cartridge will beutilized to retract the loading and firing mechanism of the firearm.

Still another object of that invention is to provide gas-operated meansin a firearm of the above nature, which will cause the gas pressuredeveloped in the barrel to be imposed directly upon one of the principalparts of the loading and firing mechanism thereof.

A further object is to provide an improved form of gas-operated firearmwhich will be relatively inexpensive to manufacture, simple inconstruction, of few parts, and which is very efilcient and durable inuse.

With these and other objects in View, which will appear as thedescription proceeds, there has been illustrated in the accompanyingdrawings one form in which the invention may be embodied in practice.

In the drawings, wherein like reference numerals designate like partsthroughout the several views:

Figure 1 is a side elevational view of a small calibre firearm embodyingthe features and principles of this invention;

Figure 2 is a longitudinal sectional view through the receiver andbreech end of the barrel of the firearm shown in Figure 1;

Figure 3' is a sectional view similar to Figure 2 but'with the loadingand firing mechanism of the firearm shown in retracted position;

Figure 4 is a cross-sectional View taken on the line 4-4 of Figure 2;

Figure 5 is a broken sectional View taken on the line 5-5 of Figure 4;and

Figure 6 is a broken sectional view taken on the line 6-6 of Figure 4.

Referring to the drawings, and particularly to Figure 1, the firearmselected to illustrate the improved features and principles of thisinvention, is similar to that fully shown and described in my pendingapplication Serial No. 327,591, filed April 3, 1940, now Patent2,339,027, issued January 11, 1944. The firearm generally comprises acombined stock and forearm I 0, II respectively, a trigger guard l2, anda barrel l3, which is removably secured into the forward end of areceiver I4, and, with it, is removably secured to the forearm H by atake down screw [5, which screw 15 is screw-threaded into a post I6extending downward from the receiver M. Suitable rear and front sightsI! and 18 respectively are also provided.

As described in the above referred to application, the receiver I4 isprovided with a slot I9 to allow the ejection of empty cartridge cases,and the barrel I3 is provided with the usual cartridge receiving chamber2| formed in its rear, or breech, end 22, to receive a cartridge 23 fed,or inserted into the receiver as in this instance, through an opening 24provided in the upper surface of the receiver M.

The cartridge 23, when inserted into the receiver I4, is adapted to beengaged and firmly seated in said chamber 2|, and fired While therein,by a bolt 25 which is slidably mounted in the receiver I4. The forwardend of the bolt 25 is counterbored, as at 26, to receive the head 21 ofthe cartridge 23, and has a primer striking lug 28 protruding therefromin position to strike the cartridge primer and thus fire the cartridge.A cartridge case extracting and ejecting spring finger 29 is secured tothe bolt 25 by a screw 3| and extends forwardly along the bolt, in agroove 32 provided therefor, into position to dispose a hook end 33thereof under the cartridge head 21, when the bolt 25 is slid into itforward position, and thereby adapt it to draw the cartridge case fromthe chamber 2| when the bolt 25 is retracted. The arrangement is suchthat after the cartridge case has been fully withdrawn from the chamber22 it will be thrown downwardly and out of the opening H! by the finger29 acting, through the hook end 33, upon the cartridge case head.

The bolt 25 is constantly under the tension of a driving spring 34 whichis disposed in a bore 35, provided in the bolt, and reacts between thebolt and a rear end plug 36 secured in the rear end of the receiver M todrive the bolt 25 forwardly to position its forward face into closeproximity to the rear face of the breech end of the barrel. A thumbenga-geable knurled member 31 extends outwardly from the bolt 25 throughan elongated opening 38 (Fig. 1) formed in the side of the receiver M,whereby the bolt 25 may be retracted by hand against the tension of thespring 34 and be guided in its to and fro movements in axial alignmentwith the barrel I3. In this instance the bolt is adapted to bereleasably held in its retracting position and against th action of thespring 34, by the cooperation between a shoulder 39 provided on theundersurface of the bolt 25 and a hooked end 40 provided on an arm 4|formed on a trigger 42 which is pivoted to the receiver I4 by a pin 43.slight pull on a finger piece M of the trigger 42 against the action ofa trigger spring 55 will disengage the hooked end 45 from the shoulder39 on the bolt 25 to permit the spring 36 to act to drive the bolt 25forwardly and thereby fire a cartridge 23 disposed in the chamber 2While in the above referred to application the recoil action caused byfiring a cartridge was entirely relied upon to retract the bolt 25,means is provided herein for utilizing the gas pressure developed in thebarrel l3 when a cartridge 23 is fired. In contradistinction to many ofthe well known forms of gas-operated firearms, the bolt 25, or firearmloading and firing means, is retracted by means of this inventionsubstantially simultaneously with the firing of the cartridge and notafter the cartridge ball, or bullet, has traversed the greater part ofthe length of the barrel. By the use of the herein disclosed means gaspressure acts directly upon the bolt 25 to retract it as the bulletleaves the cartridge case, thus effecting a more speedy action in theoperation of the firearm. By causing the gas pressure to act directlyupon the bolt 25, as is illustrated herein, no lost motion isexperienced as would be if connections were made through the usuallyprovided various levers and sliding parts.

The above referred to means to utilize the gas pressure as soon asdeveloped in the barrel by the firing of a cartridge 23 comprises, inits simplest form, a duct leading from the rear end face of the breechend 22 of the barrel E3 to a position directly forward of the front end,or case shoulder, 52 of the chamber 2|. The duct 5| is connected, atthis point, to the bore 53 in the barrel l3 by a cross duct 54. By meansof the ducts 5| and 54 gas pressure developed in the barrel as soon asthe cartridge 23 is fired acts upon the loading and/or firing mechanismto retract it. In the form illustrated this action is upon a portion ofthe forward face of said bolt 25, said face being constituted herein bythe end face of a stud 55 extending from the bolt 25 and into the duct5|. As illustrated, the stud 55 acts within the duct 5| similarly to theaction of a piston within a cylinder.

To facilitate manufacture, the breech end of the barrel H5 is extendedrearwardly in the form of a lip, or tongue, 56 to overlie a horizontalsurface 51 formed on the bolt 25 by cutting away part of the forward endof the bolt. The cutting away of part of the bolt 25 to provide thesurface 51 forms a forwardly directed shoulder 58.

The duct 5| is extended rearwardly through the extended lip 56 inalignment with the stud The arrangement is such that a 4 55 whichextends forwardly from the face of the shoulder 58, and is adapted toenter the open end of the duct 5|.

The operation of the above described firearm is briefly as follows. Acartridge 23 is inserted into the receiver I4 and into the chamber 2|,the bolt beingheld in its retracted position by the hooked. end engagingthe shoulder 39 on the bolt. The trigger 42 is actuated to release thisengagement and the bolt 25 is driven forward by the spring 34 to enterand seat the cartridge 23 in the chamber 2| and to simultaneously firethe primer. When the cartridge is fired, gas pressure acting through theducts 5|, 54 retracts the bolt 25 whereupon the empty cartridge case isejected. As in the form illustrated recoil action will also beexperienced, a particularly fast retraction of the bolt will take placeand should any of the well known types of cartridge feeding means beemployed in combination with the features of this invention, aparticularly fast automatic firearm will be obtained.

While there has been shown and described herein, one form of an improvedfirearm, it is to be understood that the invention may be embodied inother forms without departing from the spirit or essential attributesthereof. It is, therefore, desired that the present embodiment beconsidered in all respects as illustrative and not restrictive,reference being had to the claims rather than to the foregoingdescription to in dicate the scope of the invention.

Having thus fully described the invention, what is claimed as new andfor which it is desired to secure Letters Patent is:

1. In a firearm, a receiver, a barrel having a bore, a bolt movable insaid receiver to present its forward end face into close proximity withthe breech end face of the barrel, said barrel having a rearwardlydirected tongue extending from its breech end face, said bolt being cutaway to receive said tongue and to form a forwardly directed shoulder,the barrel having a duct leading from its bore to the rear end face ofsaid tongue, and a stud extending from the forwardly directed shoulderof said bolt and adapted to enter and to close the rear open end of saidduct when the forward end face of the bolt is in close proximity withthe breech end face of the barrel.

2. In a firearm, a receiver, a barrel extending from the front end ofthe receiver and having a first bore therethrough and a cartridgereceiving chamber formed in its breech end, a bolt slidable in saidreceiver in axial alignment with said barrel, means to guide said boltin its axial movements, means to move said bolt forwardly to force acartridge into the cartridge chamber in said barrel, said bolt being cutaway at its forward end to provide a forwardly directed shoulder, atongue extending rearwardly from the breech end of said barrel andoverlapping the cut away portion of said bolt, a second bore in saidbarrel leading from the rear end of said tongue and formed in the barrelwall between the said cartridge chamber and the outer periphery of thebarrel-to form a cylinder, a duct formed in the barrel leading from thefront end of the second bore to the first bore at a point forward of thecartridge chamber in said barrel to direct exploded gases to the saidsecond bore, and a stud, forming a piston, extending from the forwardlydirected shoulder on said bolt in alignment with the second bore in saidbarrel to enter the same when the bolt is moved into position to inserta cartridge into the cartridge chamber and adapted to be expelledtherefrom by pressure of the gases formed, due to the explosion of saidcartridge, and force the bolt rearwardly away from the breech end ofsaid barrel.

3. In a firearm, a receiver, a barrel having a bore and extending fromsaid receiver, and a bolt movable on said receiver to present itsforward end face into close proximity with the breech end face of thebarrel, said bolt having a lengthwise opening extending rearwardly fromits forward end face to form a forwardly facing shoulder, said barrelhaving a portion extending rearwardly from its breech end face andadapted to be received in the opening in said bolt, said barrel having aduct leading from its bore through the rearwardly extending portion tothe rear end face thereof.

4. In a gas-operated firearm, a receiver, a barrel having a bore, a boltmovable in said receiver to present its forward end face into close 6end face of said tongue with its open end facing said shoulder in saidbolt.

5. In a firearm in accordance with claim 3 and having a stud extendingforwardly from the forwardly facing shoulder, formed by the opening insaid bolt, and adapted to enter the duct in said barrel when theadjacent bolt and barrel end faces are in close proximity.

HAROLD F. MOSSBERG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 319,595 Maxim June 9, 1885729,413 Reifgraber May 26, 1903 1,020,596 Brauning Mar. 19, 1912 FOREIGNPATENTS Number Country Date 22,098 Austria Nov. 10, 1905 45,225 AustriaDec. 10, 1910 453,658 Germany Dec. 15, 1927 593,045 Germany Feb. 20,1934

